The invention concerns a tank venting filter, in particular for a motor vehicle.
Filter systems for filtering media have been known for a long time, for example, from U.S. Pat. No. 4,470,296 A or DE 1 047 171 A.
In this context, it is also known to provide air filters for tanks, in particular for tanks of motor vehicles, by means of which the tanks can be vented with purified (ambient) air. U.S. Pat. No. 3,546,853 A and EP 1 647 320 B1 disclose, for example, tank venting filters which have at their bottom side a plurality of air inlets.
A similar tank venting filter is disclosed in U.S. Pat. No. 2,603,308 A wherein the tank venting filter comprises a chamber at its air outlet side which is delimited by two plates with small passage cutouts in order to prevent contamination of a filter element in the tank venting filter by fuel that is “splashing out” of the tank.
Moreover, EP 2 607 136 A1 discloses a tank venting valve that comprises a mechanically actuatable surge guard device in order to avoid contamination of the tank venting filter with fuel.
Finally, WO 2013/066217 A1 discloses a tank venting filter comprising a filter element that is protected by a cover from fuel possibly penetrating into the tank venting filter.
However, tank venting filters may become contaminated not only by the tank contents, for example, fuel or also a urea solution, that penetrates through an air outlet into the tank venting filter but also by water that passes through an air inlet into the tank venting filter. On the one hand, the water must not penetrate into the tank so as not to contaminate the tank contents. At the same time, the filter element of the tank venting filter must also be protected from becoming moist or completely wet so as not to compromise the performance of the filter element or the proper function of the tank venting filter.
The demands put on a tank venting filter with regard to protection of the filter from penetrating water as well as a water retention capability of the tank venting filter are relatively high, in particular because motor vehicles, when driving through rain or also in case of use of a high-pressure cleaner, are exposed to water aerosols which act with partially high pressure on the tank venting filter. Since the tank venting filter is a mass-produced article or disposable part, water protection of the tank venting filter must be simultaneously of a constructively simple design with regard to cost considerations.
It is therefore the object of the invention to provide a tank venting filter that provides an effective protection from penetrating water and, at the same time, is of a constructively simple configuration.